1. Field of the Invention
The present invention relates to a DC/DC power conversion device for converting a DC voltage into a boosted or deboosted DC voltage.
2. Description of the Background Art
Japanese Unexamined Patent Application Publication No. H9-191638 discloses a DC/DC converter as a conventional DC/DC power conversion device. The DC/DC converter is comprised of inverter circuits including semiconductor switches connected to a voltage with a positive polarity (hereinafter, abbreviated to “positive voltage”) and semiconductor switches connected to a voltage with a negative polarity (hereinafter, abbreviated to “negative voltage”) and multiplier-rectifier circuits including a plurality of rectifiers connected in series and a plurality of capacitors connected in series. The inverter circuits generate alternating current (AC) voltages and the multiplier-rectifier circuits generate high DC voltages for application to a load.
Such conventional DC/DC power conversion device includes inverter circuits and rectifier circuits with smoothing capacitors connected in parallel, and performs DC/DC power conversion using charge-discharge of capacitors which are connected in series between the inverter circuits and the rectifier circuits. In this case, the smoothing capacitors supply currents together with the capacitors connected between the circuits. Since currents flowing through the capacitors connected between the respective circuits flow through overlapping the smoothing capacitors, ripple currents flowing through the smoothing capacitors increase. This causes heat-emission to be large in the smoothing capacitors and capacitances for permission of the currents to be also large, thereby increasing the size of the smoothing capacitors.